/* ==========================================================================
   FROM COIL TO PIPE — the scroll-forming sequence.
   CSS sticky pin + one rAF loop. No libraries. Transform and opacity only.
   ========================================================================== */

.forge {
  position: relative;
  height: 340vh;
  background: var(--navy-950);
  --pipe-length: 640px;
  --slat-h: 14px;
}
@media (max-width: 899px) { .forge { height: 230vh; } }

.forge__sticky {
  position: sticky; top: 0;
  height: 100svh;
  overflow: hidden;
  display: grid;
  place-items: center;
  isolation: isolate;
}

/* Atmosphere behind the scene — a lit mill floor, not a black void. */
.forge__sticky::before {
  content: ''; position: absolute; inset: 0; z-index: 0; pointer-events: none;
  background:
    radial-gradient(70% 55% at 50% 46%, rgba(12, 70, 129, 0.30), transparent 70%),
    radial-gradient(120% 80% at 50% 118%, rgba(1, 13, 34, 0.9), transparent 60%);
}
/* Floor line — grounds the tube so it isn't floating in space. */
.forge__sticky::after {
  content: ''; position: absolute; left: 0; right: 0; bottom: 20%; height: 1px; z-index: 0;
  background: linear-gradient(90deg, transparent, rgba(113, 203, 227, 0.16) 22%, rgba(113, 203, 227, 0.16) 78%, transparent);
  pointer-events: none;
}

.forge__scene {
  position: relative; z-index: 1;
  width: 100%; height: 100%;
  display: grid; place-items: center;
  transform-origin: 50% 50%;
  will-change: transform, opacity;
}
.forge__cards { will-change: transform; }

/* --------------------------------------------------------------------------
   3D STAGE
   -------------------------------------------------------------------------- */
.forge__stage {
  position: absolute; inset: 0;
  perspective: 1700px;
  transform-style: preserve-3d;
  display: grid; place-items: center;
}

.forge__pipe {
  position: absolute; left: 50%; top: 50%;
  width: 0; height: 0;
  transform-style: preserve-3d;
  will-change: transform;
}

/* Each slat is one thin strip running the full length of the pipe at a fixed
   circumferential angle. 48 of them close into a cylinder of radius W / 2pi. */
.forge__slat {
  position: absolute; left: 0; top: 0;
  width: var(--pipe-length);
  height: calc(var(--slat-h) + 0.6px);   /* 0.6px overlap kills hairline gaps */
  margin-left: calc(var(--pipe-length) / -2);
  margin-top: calc((var(--slat-h) + 0.6px) / -2);
  transform-style: flat;
  /* Rolled-steel base: light falls off along the axis. No per-slat edge
     highlight — 48 of those read as corrugation, not as a smooth surface. */
  background-image:
    repeating-linear-gradient(90deg, rgba(0,0,0,0.045) 0 2px, transparent 2px 5px),
    linear-gradient(90deg,
      #141317 0%, #2f353c 5%, #5d656f 14%, #838c97 24%, #a2abb6 33%,
      #8d96a1 41%, #737b86 52%, #575e68 65%, #3b424a 79%, #23282e 91%, #121519 100%);
}

/* Promoted only while the section is on screen, dropped again on exit. */
.forge__pipe.is-live { will-change: transform; }
.forge__pipe.is-live .forge__slat { will-change: transform, filter; }

/* --------------------------------------------------------------------------
   COIL  (stage 01)
   -------------------------------------------------------------------------- */
.forge__coil {
  position: absolute; top: 50%; left: clamp(-70px, -3vw, -10px);
  transform: translateY(-50%);
  width: clamp(190px, 20vw, 280px); height: auto;
  z-index: 2; pointer-events: none;
}
.forge__coil svg { width: 100%; height: auto; }
.forge__coil .cl-arc { fill: none; stroke: rgba(169, 182, 198, 0.5); stroke-width: 1.1; }
.forge__coil .cl-arc-hi { stroke: rgba(113, 203, 227, 0.55); }
.forge__coil .cl-core { fill: rgba(1, 13, 34, 0.9); stroke: rgba(113, 203, 227, 0.4); stroke-width: 1.2; }
.forge__coil .cl-body { fill: rgba(35, 44, 53, 0.55); stroke: rgba(169, 182, 198, 0.35); stroke-width: 1; }

/* --------------------------------------------------------------------------
   SLITTING GUIDES + DIMENSION CALLOUT  (stage 02)
   -------------------------------------------------------------------------- */
.forge__slit { position: absolute; inset: 0; z-index: 3; pointer-events: none; }
.forge__guide {
  position: absolute; left: 50%; top: 50%;
  width: clamp(260px, 46vw, 720px); height: 1px;
  margin-left: calc(clamp(260px, 46vw, 720px) / -2);
  background: linear-gradient(90deg, transparent, var(--cyan-400) 18%, var(--cyan-400) 82%, transparent);
  opacity: 0;
}
.forge__guide::after {
  content: ''; position: absolute; right: -1px; top: -4px;
  width: 1px; height: 9px; background: var(--cyan-400);
}
.forge__dim {
  position: absolute; left: 50%; top: 50%;
  transform: translate(-50%, -50%);
  font-family: var(--font-mono); font-size: 0.6875rem; letter-spacing: 0.1em;
  color: var(--cyan-400); background: rgba(1, 13, 34, 0.86);
  border: 1px solid rgba(113, 203, 227, 0.35); border-radius: 2px;
  padding: 5px 10px; white-space: nowrap; opacity: 0;
}

/* --------------------------------------------------------------------------
   FORMING ROLLS  (stage 03)
   -------------------------------------------------------------------------- */
.forge__rolls { position: absolute; inset: 0; z-index: 4; pointer-events: none; }
.forge__roll {
  position: absolute; left: 50%; top: 50%;
  width: 96px; height: 96px; margin: -48px 0 0 -48px;
  opacity: 0;
}
.forge__roll .rl-body { fill: rgba(18, 23, 29, 0.92); stroke: rgba(169, 182, 198, 0.45); stroke-width: 1.4; }
.forge__roll .rl-rim  { fill: none; stroke: rgba(113, 203, 227, 0.4); stroke-width: 1; }
.forge__roll .rl-groove { stroke: rgba(113, 203, 227, 0.30); stroke-width: 1.1; fill: none; }
.forge__roll .rl-spoke { stroke: rgba(169, 182, 198, 0.4); stroke-width: 1.2; }
.forge__roll .rl-hub  { fill: rgba(47, 58, 69, 0.9); stroke: rgba(169, 182, 198, 0.5); stroke-width: 1; }

/* SVG groups spun from JS need an explicit box to rotate about. */
.rl-spin, .forge__coil-spin { transform-box: fill-box; transform-origin: 50% 50%; }

/* --------------------------------------------------------------------------
   WELD SEAM + GLOW  (stage 04)  — lives inside the 3D scene
   -------------------------------------------------------------------------- */
/* The seam sits at alpha = PI, so its element carries rotateX(180deg). That
   flips Y and Z but leaves X alone, so the glow still travels left to right
   and the bar's own gradient is vertically symmetric. No mirror correction. */
.forge__seam {
  position: absolute; left: 0; top: 0;
  width: var(--pipe-length); height: 5px;
  margin-left: calc(var(--pipe-length) / -2); margin-top: -2.5px;
  opacity: 0;
  background: linear-gradient(to bottom,
    rgba(1,13,34,0.5) 0%, rgba(140,42,0,0.55) 30%, rgba(206,206,206,0.75) 50%,
    rgba(140,42,0,0.55) 70%, rgba(1,13,34,0.5) 100%);
}

/* Hot core with a ~200px cooling trail behind it: white-hot core, amber,
   dull red, back to steel. One element, translated in X. */
.forge__glow {
  position: absolute; top: 50%; left: 50%;
  width: 280px; height: 30px; margin-top: -15px; margin-left: -140px;
  border-radius: 50%;
  background: linear-gradient(90deg,
    rgba(90, 24, 0, 0) 0%, rgba(120, 30, 0, 0.42) 22%,
    rgba(176, 44, 0, 0.66) 42%, rgba(232, 96, 12, 0.84) 60%,
    rgba(255, 150, 52, 0.94) 74%, rgba(255, 214, 150, 1) 86%,
    rgba(255, 243, 214, 1) 94%, rgba(255, 243, 214, 0.86) 100%);
  opacity: 0;
}

/* Cyan rim light. The per-slat filter is monochrome, so the cool edge the
   metal needs is carried by one tinted bar sitting at the rim angle. */
.forge__rim {
  position: absolute; left: 0; top: 0;
  width: var(--pipe-length); height: 14px;
  margin-left: calc(var(--pipe-length) / -2); margin-top: -7px;
  background: linear-gradient(to bottom,
    transparent, rgba(113, 203, 227, 0.42) 45%, rgba(160, 220, 240, 0.55) 52%,
    rgba(113, 203, 227, 0.30) 62%, transparent);
  opacity: 0; pointer-events: none;
}

/* Longitudinal mill scale on the raw strip, polished away by stage 03. */
.forge__millscale {
  position: absolute; left: 0; top: 0;
  opacity: 0; pointer-events: none;
  background-image:
    repeating-linear-gradient(0deg,
      rgba(20, 14, 8, 0.22) 0 2px, transparent 2px 7px,
      rgba(60, 48, 32, 0.14) 7px 9px, transparent 9px 16px);
}

/* Radial heat bloom on the slats around the seam, travelling with the head. */
.forge__heat {
  position: absolute; left: 0; top: 0;
  width: 300px; height: 190px; margin-left: -150px; margin-top: -95px;
  border-radius: 50%;
  background: radial-gradient(closest-side,
    rgba(255, 200, 120, 0.42) 0%, rgba(255, 122, 24, 0.24) 38%,
    rgba(140, 42, 0, 0.12) 66%, transparent 100%);
  opacity: 0;
}

/* --------------------------------------------------------------------------
   WELD HEAD  (2D overlay, positioned from the projected seam point)
   -------------------------------------------------------------------------- */
.forge__head {
  position: absolute; left: 0; top: 0;
  width: 68px; height: 82px; margin: -41px 0 0 -34px;
  z-index: 6; opacity: 0; pointer-events: none;
  filter: drop-shadow(0 0 14px rgba(255, 138, 43, 0.35));
}
.forge__head .hd-box { fill: rgba(18, 23, 29, 0.95); stroke: var(--cyan-400); stroke-width: 1.2; }
.forge__head .hd-fin { stroke: rgba(169, 182, 198, 0.6); stroke-width: 1.2; }
.forge__head .hd-tip { fill: var(--weld-hot); }
.forge__head .hd-coil { fill: none; stroke: rgba(255, 138, 43, 0.85); stroke-width: 1.4; }

/* --------------------------------------------------------------------------
   END CAP + FLANGE  (stages 05 / 06) — inside the 3D scene
   -------------------------------------------------------------------------- */
.forge__endcap {
  position: absolute; left: 0; top: 0;
  border-radius: 50%;
  background:
    radial-gradient(closest-side, rgba(18,23,29,0.98) 0 62%, rgba(120,129,139,0.9) 63%, rgba(58,66,75,0.95) 100%);
  box-shadow: inset 0 0 0 1px rgba(206, 206, 206, 0.35);
  opacity: 0;
}
.forge__flange {
  position: absolute; left: 0; top: 0;
  opacity: 0;
}
.forge__flange svg { width: 100%; height: 100%; display: block; }
.forge__flange .fl-face { fill: #2c333b; stroke: rgba(206,206,206,0.55); stroke-width: 1.4; }
.forge__flange .fl-raise { fill: #454e59; stroke: rgba(214,214,212,0.45); stroke-width: 1.1; }
.forge__flange .fl-bore { fill: #0b0f13; stroke: rgba(206,206,206,0.45); stroke-width: 1.2; }
.forge__flange .fl-bolt { fill: #10141a; stroke: rgba(169,182,198,0.5); stroke-width: 1; }
.forge__flange .fl-etch { opacity: 0; }

/* --------------------------------------------------------------------------
   CUT LINE  (stage 05)
   -------------------------------------------------------------------------- */
.forge__cut {
  position: absolute; left: 50%; top: 50%;
  width: 2px; height: 42vh; margin-top: -21vh;
  background: linear-gradient(to bottom, transparent, var(--weld-hot) 25%, var(--weld-hot) 75%, transparent);
  box-shadow: 0 0 12px rgba(255, 243, 214, 0.55);
  opacity: 0; z-index: 5; pointer-events: none;
}

/* --------------------------------------------------------------------------
   SPARKS CANVAS  (stage 04)
   -------------------------------------------------------------------------- */
.forge__sparks {
  position: absolute; inset: 0; z-index: 7;
  width: 100%; height: 100%; pointer-events: none;
}

/* --------------------------------------------------------------------------
   STAGE CARDS
   -------------------------------------------------------------------------- */
.forge__cards {
  position: absolute; z-index: 8; pointer-events: none;
  left: var(--gut); bottom: 92px; right: var(--gut);
}
@media (min-width: 900px) {
  .forge__cards {
    left: var(--gut); right: auto; top: 50%; bottom: auto;
    transform: translateY(-50%);
    width: min(30vw, 360px);
  }
}

.forge__card {
  position: absolute; left: 0; bottom: 0; width: 100%;
  opacity: 0; transform: translateY(12px);
  transition: opacity 260ms var(--ease), transform 260ms var(--ease);
}
@media (min-width: 900px) { .forge__card { bottom: auto; top: 0; } }
.forge__card.is-on { opacity: 1; transform: none; }

.forge__card-n {
  font-family: var(--font-mono); font-size: 0.6875rem; letter-spacing: 0.18em;
  color: var(--cyan-400); display: flex; align-items: center; gap: 10px; margin-bottom: 14px;
}
.forge__card-n::before { content: ''; width: 22px; height: 1px; background: currentColor; opacity: 0.6; }
.forge__card-t {
  font-family: var(--font-display); font-stretch: 125%; font-weight: 700;
  font-size: clamp(1.375rem, 2.4vw, 2rem); line-height: 1.08; letter-spacing: -0.02em;
  color: var(--text-hi);
}
.forge__card-d { color: var(--text-mid); font-size: 0.9375rem; line-height: 1.6; margin-top: 14px; max-width: 42ch; }
.forge__card-s {
  display: inline-block; margin-top: 16px; padding: 7px 11px;
  font-family: var(--font-mono); font-size: 0.6875rem; letter-spacing: 0.04em;
  color: var(--text-hi); background: rgba(1, 13, 34, 0.7);
  border: 1px solid rgba(113, 203, 227, 0.28); border-radius: 2px;
}
@media (max-width: 899px) {
  .forge__card-d { display: none; }
  .forge__cards { bottom: 76px; }
}

/* --------------------------------------------------------------------------
   PROGRESS RAIL  (desktop only)
   -------------------------------------------------------------------------- */
.forge__rail {
  position: absolute; right: var(--gut); top: 50%; transform: translateY(-50%);
  z-index: 8; display: none; gap: 2px; flex-direction: column; pointer-events: none;
}
@media (min-width: 1080px) { .forge__rail { display: flex; } }

.forge__tick { display: flex; align-items: center; gap: 12px; justify-content: flex-end; height: 46px; }
.forge__tick-l {
  font-family: var(--font-mono); font-size: 0.625rem; letter-spacing: 0.12em;
  text-transform: uppercase; color: var(--text-low);
  transition: color 260ms var(--ease); text-align: right;
}
.forge__tick-b {
  position: relative; width: 2px; height: 100%; background: rgba(233, 238, 245, 0.12); flex: none;
}
.forge__tick-b i {
  position: absolute; inset: 0; background: var(--cyan-400);
  transform: scaleY(0); transform-origin: top;
  transition: transform 120ms linear;
}
.forge__tick.is-on .forge__tick-l { color: var(--cyan-400); }


/* --------------------------------------------------------------------------
   WELCOME MOMENT
   The payoff at the end of the scroll: the mark lifts off the flange face,
   the wordmark resolves under it, a cyan hairline draws outward from centre.
   Carries the page's only <h1>, present in the HTML from first paint.
   -------------------------------------------------------------------------- */
.forge__welcome {
  position: absolute; left: 0; right: 0; top: 50%;
  transform: translate3d(0, -50%, 0);
  z-index: 9; opacity: 0; pointer-events: none;
  padding-inline: var(--gut);
  text-align: center;
  will-change: transform, opacity;
}
.forge__wmark {
  width: clamp(56px, 8vw, 84px); height: auto; margin: 0 auto 26px;
  transform-origin: 50% 50%;
}
.forge__weyebrow {
  font-family: var(--font-mono); font-size: 0.6875rem; font-weight: 500;
  letter-spacing: 0.24em; text-transform: uppercase; color: var(--cyan-400);
  margin-bottom: 16px;
}
.forge__wtitle { margin: 0; font-weight: 400; }
.forge__wname {
  display: block;
  font-family: var(--font-display); font-stretch: 125%; font-weight: 700;
  font-size: clamp(1.75rem, 4.4vw, 3.5rem); line-height: 1.02;
  letter-spacing: -0.025em; color: var(--text-hi); text-wrap: balance;
}
.forge__wrule {
  display: block; width: min(320px, 60vw); height: 1px; margin: 26px auto 0;
  background: linear-gradient(90deg, transparent, var(--cyan-400), transparent);
  transform: scaleX(0); transform-origin: 50% 50%;
}
.forge__wsub {
  display: block; margin-top: 22px;
  font-family: var(--font-mono); font-size: 0.75rem; font-weight: 400;
  letter-spacing: 0.16em; text-transform: uppercase; color: var(--text-mid);
  line-height: 1.7;
}
/* The rail and stage cards step aside once the brand moment takes over. */
.forge.is-welcome .forge__rail { opacity: 0; transition: opacity 400ms var(--ease); }

/* Closing line under the sequence. */
.forge__outro {
  position: absolute; left: 50%; transform: translateX(-50%);
  bottom: 28px; z-index: 8; opacity: 0;
  transition: opacity 400ms var(--ease);
}
.forge__outro.is-on { opacity: 1; }
@media (max-width: 899px) { .forge__outro { display: none; } }

/* --------------------------------------------------------------------------
   STATIC / REDUCED-MOTION VARIANT
   Not a degraded version — a deliberate one. The finished pipe is rendered
   once, and the six stages become a readable technical list.
   -------------------------------------------------------------------------- */
.forge.forge--static { height: auto; }
.forge--static .forge__sticky { position: relative; height: auto; display: block; overflow: visible; }
.forge--static .forge__scene { height: 62svh; min-height: 420px; transform: none; opacity: 1; }
.forge--static .forge__welcome { position: static; transform: none; opacity: 1; padding-block: 0 clamp(32px,5vw,56px); }
.forge--static .forge__rail { display: none; }
.forge--static .forge__rail,
.forge--static .forge__sparks,
.forge--static .forge__coil,
.forge--static .forge__rolls,
.forge--static .forge__slit,
.forge--static .forge__head,
.forge--static .forge__cut,
.forge--static .forge__outro { display: none; }

.forge--static .forge__cards {
  position: static; transform: none; width: auto; pointer-events: auto;
  display: grid; gap: 1px;
  max-width: var(--max); margin: 0 auto; padding: 0 var(--gut) clamp(56px, 7vw, 96px);
}
@media (min-width: 760px) { .forge--static .forge__cards { grid-template-columns: repeat(2, 1fr); gap: 1px; } }
@media (min-width: 1080px) { .forge--static .forge__cards { grid-template-columns: repeat(3, 1fr); } }

.forge--static .forge__card {
  position: static; opacity: 1; transform: none; transition: none;
  padding: 28px 26px; background: var(--navy-900);
  outline: 1px solid rgba(113, 203, 227, 0.14);
}
.forge--static .forge__card-d { display: block; }

/* The no-JS path shows the same static list — core content never needs JS. */
.no-js .forge { height: auto; }
.no-js .forge__sticky { position: relative; height: auto; display: block; }
.no-js .forge__scene { display: none; }
.no-js .forge__welcome { position: static; transform: none; opacity: 1; padding: clamp(56px,8vw,104px) var(--gut) 0; }
.no-js .forge__cards { position: static; transform: none; width: auto; display: grid; gap: 1px; max-width: var(--max); margin: 0 auto; padding: clamp(56px,7vw,96px) var(--gut); }
@media (min-width: 760px) { .no-js .forge__cards { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 1080px) { .no-js .forge__cards { grid-template-columns: repeat(3, 1fr); } }
.no-js .forge__card { position: static; opacity: 1; transform: none; padding: 28px 26px; background: var(--navy-900); outline: 1px solid rgba(113,203,227,0.14); }
.no-js .forge__card-d { display: block; }
.no-js .forge__rail { display: none; }